Effect of temperature in cathodic electrodeposition of anatase TiO2 films on conductive glass

Abstract

Polycrystalline titania (TiO2) films were prepared on the ultrasonically cleaned indium tin oxide glass (ITO) substrates on high temperature annealing of TiO2 hydrates electrodeposited from the chemical bath of titanyl sulphate at room temperature and above. The film grew in thickness monotonically from 53nm to 113nm with the rise in bath temperature at constant bath deposition time. The bath temperature was found to be important for the extent to which the anatase phase was achieved for a given set of annealing temperatures and deposition times. The Raman spectra of the annealed films which were deposited at the bath temperature of 336K exhibited distinct anatase phase. Optical (UV/vis absorption) in the annealed TiO2 was found to be due to indirect allowed transitions over the band gap of 3.4eV. The experimental data was analysed in Tauc and Urbach regions. The Urbac energy obtained for the films deposited at 336K was equal to 0.26eV and showed an almost linear relationship. The transformation from amorphous to crystalline structure on annealing was ob-served in the XRD pattern and the AFM images. The grain size was estimated to be 88nm from XRD measurements. The correct stoichiometry of the TiO2 film was achieved according to the X-ray photoelectron analysis. An extended study including interactions between temperature of the bath and deposition potential is finally recommended to optimise even more the film preparation method.